feedc0de/qt-creator
1
0
Fork 0
forked from qt-creator/qt-creator
Code Pull Requests Activity

Doc: Improve CPU Usage Analyzer documentation

Browse Source 
Add sections about extra command line options and troubleshooting.

Change-Id: I2ecd7b32a211321bcf9c31ee65f92386b70958db
Reviewed-by: Kari Hautamäki <kari.hautamaki@theqtcompany.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
This commit is contained in:
Ulf Hermann
2015-04-16 15:17:17 +02:00
parent ffc2613d32
commit 8e957f09c7
1 changed files with 30 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
doc/src/analyze/cpu-usage-analyzer.qdoc
View File

@@ -132,6 +132,14 @@
data, and the processing delay may grow excessively. You should then lower
the \uicontrol {Sampling frequency} or the \uicontrol {Stack snapshot size}.
\section2 Adding Command Line Options For Perf
You can specify additional command line options to be passed to Perf when
recording data in the \uicontrol {Additional arguments} field. You may want
to specify \c{--no-delay} or \c{--no-buffering} to reduce the processing delay.
However, those options are not supported by all versions of Perf and Perf may
not start if an unsupported option is given.
\section1 Analyzing Collected Data
The \uicontrol Timeline view displays a graphical representation of CPU
@@ -248,4 +256,26 @@
back its own data in a sensible way by checking the output of
\c {perf report} or \c {perf script} in the recorded Perf data files.
\section1 Troubleshooting
The CPU Usage Analyzer might fail to record data for the following reasons:
\list 1
\li The connection between the target device and the host may not be
fast enough to transfer the data produced by Perf. Try lowering
the \uicontrol {Stack snapshot size} or
\uicontrol {Sampling Frequency} settings.
\li Perf may be buffering the data forever, never sending it. Add
\c {--no-delay} or \c {--no-buffering} to the
\uicontrol {Additional arguments} field.
\li Some versions of Perf will not start recording unless given a
certain minimum sampling frequency. Try with a
\uicontrol {Sampling Frequency} of 1000.
\li On some devices, Perf support is not very stable and the Linux
kernel may randomly fail to record data after some time. Reboot the
device and try again.
\endlist
Output from the helper program that processes the data is displayed in the
\uicontrol {General Messages} output pane.
*/